A number of scientific articles have been published regarding experiments directed to associating specific activity, such as vision, with specific areas of the human brain. Some of these experiments involve invasive techniques on animals, for example, the use of implanted electrodes or chemical dyes.
However, other studies have taken a different approach and have attempted to discover what happens in a person's brain when a person performs a task, like raising his finger, by placing electrodes or other sensors on or near the person's scalp. Those electrodes or sensors detect the tiny, microvolt or femtotesla level, electrical or magnetic activity at the surface of the scalp.
The detection of such faint brain wave signals is difficult because of the noisy electrical and magnetic environment created by hundreds of cars, electric lights, etc., etc. In addition, physiological "artifacts", which are electrical signals arising, for example, from scalp muscle activity or the eye blink of the subject, may produce an electrical and magnetic wave which is stronger than the subject's brain waves.
The detection and analysis of brain waves is even more difficult when the interest is in locating the specific three-dimensional sites giving rise to the waves and how the sites communicate with each other deep within the brain, as the subject responds to stimuli.
As an example of stimulus presentation, a subject is placed before a TV monitor. The letter "V" appears. If it slants to the left, the subject is to get ready to push a button with his left hand when a number appears on the monitor, and, if it slants to the right, he should get ready to push a button with his right hand. This is a simple task. But it has proven difficult to localize and display, in a readily comprehendable form, the dynamic brain wave activity ("mass neuroelectric processes") which give rise to the subject's ability to recognize the stimuli, i.e., to recognize the "V" and the subsequent number (cognitive behavior) and to physically react (perceptumotor), i.e., move his hand.
There are not now presently commercially available any non-invasive methods or systems which will locate selected brain sites, and display what occurs at those sites in response to stimuli and responses, in an accurate three-dimensional appearing display.